Purpose: To a large extent, the recent global instability is responsible for the rapid structural mutation of the career landscape, thereby affecting individuals’ career development, especially expatriates who are subjected to an acculturation process. Even though the cultural element exists in the career development literature, the implications of expatriate acculturation (EA) on individual expatriates’ career competence (CC) and career sustainability (CS) remain understudied. Therefore, this study proposes to fill this gap in literature by exploring the intrinsic role EA plays in regulating the CC–CS interactions.Design/methodology/approach: For a more comprehensive analysis, we attempt to identify the effect on each dimension of CC, thus Reflective, Social, and Behavioural competencies (RC, SC, and BC), in the case of Chinese University postgraduate alumni from Africa. We conducted a double-layer analysis with 389 respondents’ data samples.Findings/results: Results reveal that, at the aggregate level, the positive relationship between CC and CS is weakened by EA in the case of African postgraduates who studied at Chinese universities. The detailed analyses reveal that the negative effect of EA significantly undermines the RC–CS mechanism, but significantly strengthens the BC–CS interaction. Besides, the SC–CS mechanism is not significantly moderated by EA despite the negative acculturation tendencies.Practical implications: From the perspective of international interdependence, this research elucidates the magnitude and diversity of expatriates’ contribution to the host country’s career ecosystem.Originality/value: Investigating from the career construction theory (CCT) perspective, this article aims to fill this gap by finding the moderating effect of EA on the CC–CS mechanisms.